Seamless tubular net and method of making the same

ABSTRACT

A SEAMLESS TUBULAR NET IS MADE ON A WRAP KNITTING MACHINE HAVING TWO NEEDLE BEDS AND THREE GUIDE BARS, THE YARNS OF TWO BARS KNITTING WARP CHAINS, AND THE THIRD GUIDE BAR LAYING-IN A YARN TO CONNECT THE CHAINS IN TWO LAYERS. THE LAID-IN YARN IS SHIFTED STEPWISE IN A WALEWISE DIRECTION SO THAT IT FORMS A HELIX IN THE FINISHED NET. THE CIRCUMFERENTIALLY CONSECUTIVE PORTIONS OF THE LAID-IN YARN CONNECT CHAIN STITCHES IN THE SAME COURSE SO THAT THE SEVERAL TURNS OF THE HELIX ARE BOUND TO STITCHES IN THE SAME CHAIN WHICH ARE SEPARATED BY STITCHES FREE FROM LAID-IN YARN.

sept. 21.1971 3,606,710

'NSEAMLESS TUBULAR NET AND METHOD OF MAKING THE SAME A K. Kom.`

Filed Dec. 18, 1968 United States Patent O1 hee 3,606,770 SEAMLESSTUBULAR NET AND METHOD OF MAKING THE SAME Karl Kohl, OffenbacherLandstr. 20, Hanstadt am Main, Germany Filed Dec. 1s, 196s, ser. No.784,835 Claims priority, application Germany, Dec. 20, 1967, P 16 35875.1 Int. Cl. D04b 23/02 U.S. Cl. 66-87 2 Claims ABSTRACT OF THEDISCLOSURE A seamless tubular net is made on a wrap knitting machinehaving two needle beds and three guide bars, the yarns of two barsknitting warp chains, and the third guide bar laying-in a yarn toconnect the chains in two layers. The laid-in yarn is shifted stepwisein a walewise direction so that it forms a helix in the nished net. Thecircumferentially consecutive portions of the laid-in yarn connect chainstitches in the same course so that the several turns of the helix arebound to stitches in the same chain which are separated by stitches freefrom laid-in yarn.

BACKGROUND OF THE INVENTION This invention relates to seamless tubularnets knitted on a warp-knitting machine having two needle beds, and to amethod of operating the machine so as to produce the net.

It is known to produce tubular nets by connectin-g the several chainsknitted on two needle beds by means of laid-in yarns which connect twoor three adjacent chaims. The fabric so produced may constitute aseamless net, but its chains are thick relative to the yarn employed forpreparing them. If it is desired to use elastic laying-in yarn, theexpenditure for the elastic yarn is so high as to make the seamless tubeeconomically unattractive for many applications for which it wouldotherwise be emiently suitable.

A primary object of the invention is the provision of a warp-knitted,seamless, tubular net in which the amount of elastic yarn employed canbe reduced to the minimum required for adequate mechanical strength, andis minimal if little strength is needed.

SUMMARY OF THE INVENTION In the net of the invention, circumferentiallyconsecutive portions of one laid-in yarn are bound in respective spacedchains to stitches aligned in a circumferential or coursewise direction,but the consecutve portions of the laid-in yarn are offset in the samewalewise direction, which is axial relatve to the tube into which thefabric may be expanded. The laid-in yarn thus extends about the axis ofthe expanded tubular net in an approximate helix.

The several turns of the helix are bound in each chain to stitches ofthe chain which are separated from each other by at least two chainstitches free from the laid-in yarn. The walewise offset of the laid-inyarn portions is provided by linking portions of the yarn which extendaxially in the chain which extends between the two coursewiseconsecutive portions of the laid-in yarn.

' For a tubular net having a given number of Warp chains, the amount oflaid-in yarn employed may be varied to suit requirements of mechanicalstrength or mesh size by varying the number of gaps between adjacentchains that are spanned by the laid-in yarn in the same course. Aminimum of laid-in yarn is used for a given length of tubular net, ifthe laid-in yarn spans only one such gap before shifting to the nextcourse, but

3,606,770 Patented Sept. 21, 1971 two or more gaps may be spanned by thelaid-in yarn in the same course to provide a desired small mesh size 0rhigher circumferential strength. The length of each coursewise portionof the laid-in yarn is preferably, though not necessarily, equal. Asingle laid-in yarn is adequate under most conditions.

Several methods for making the above-described tubular net will readilysuggest themselves to those skilled in the art. In a method which hasbeen found particularly advantageous, the needles in each of the frontand rear beds are spaced apart and respectively knit two layers ofspaced warp chains which are connected into a tube by the laid-in yarnin a manner basically known in itself. The tube is expanded by pullingthe marginally connected layers apart.

Two guide bars are threaded with the yarns for the warp chains in thetwo layers, and a third guide bar is threaded with the laying yarn. Thepattern wheel or chain which causes the Shogging motion of the thirdguide bar is selected in such a manner that sequential portions of thelaying-in yarn are offset in a common walsewise direction, each portionbeing laid coursewise between a plurality of respective stitches of thechains which are aligned in a coursewise direction, and being bound tothe associated aligned stitches.

The lapping movements of the third yarn guide are such that thelaying-in yarn is looped about the needles of the front bed while movingfrom the left to the right along all active needles of the needle beds,while being prevented from making loops about the needles of the rearbed, the opposite procedure being observed during novement of the thirdguide bar from the right to the eft.

Other features, additional objects and many of the attendant advantagesof this invention will readily be appreciated as the same becomes betterunderstood from the following description when considered in connectionwith the appended drawing.

of the third yarn guide in making the fabrics of FIGS. 2a and 2b.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing indetail, and initially to FIG. l, there is seen a tubular seamless net ofthe invention in the expanded condition. The net consists of nine chainsof warp stitches widely separated from each other in a circumferentialor coursewise direction, and held together by a single, laid-in, elasticyarn 2 in the manner shown in FIG. la. On the relatively small scale ofFIG. l, the laid-in yarn 2 appears to form a continuous helix about theaxis of the net, its several turns being spaced widely in an axial orwalewise direction so that a substantial number of chain stitchesbetween successive turns is free from the laid-in yarn in each chain.

Details of the disposition of the laid-in yarn in respective tubularnets of the invention are better seen in FIGS. 2a, 2b, and 2c which shownets closely similar to that of FIG. 1 in diagrammatic, developed views.'I'he nine Warp chains 1a, 1b, 1c, etc. are knitted on a machine havingtwo needle beds in which the needles are spaced from each other by meansof two correspondingly threaded guide bars n a known manner to form twolayers of chains which may be separated in the middle while beingconnected at the edges by means of laid-in yarn.

As is shown in FIG. 2a, the laying-in yarn connects the chains 1a, 1b inthe course 3a being bound to the respective stitches of the two chains.The yarn then progresses walewise in the chain 1b by one course spacinginto the course 3b in which it similarly connects the chains 1b and 1c.This procedure is repeated until the laid-in yarn reverts to the chain1a in a course offset walewise by nine stitches from the course 3a.

In the `fabric indicated in FIG. 2b, the laid-in yarn 2 extends over thetwo gaps between the chains 1a, 1b, 1c in the same course, then shiftsto the course 3b for bridging the next two gaps, and reverts to thechain '1a in the fth course. Each coursewise portion of the laid-in yarnis bound to the three stitches of the connected chains a which arealigned in a coursewise direction.

Yet another arrangement is illustrated in FIG. 2c in which the laid-inyarn 2 spans four gaps in the course 3a to connect ve chains beforeswitching to the course 3b in which it again bridges four gaps. Theapproximate helix formed by the laid-in yarn 2 in the fabric illustratedin FIG. 2c has one half the pitch of the helix in FIG. 2b and onequarter the pitch of the helix in FIG. 2a. While the number of chainsconnected by the same coursewise run of the laid-in fabric is the samein each of FIGS. 2a, 2b, 2c, and each step of the helix is one coursehigh, the pattern chain or pattern wheel controlling the shogging motionof the third or laying-in yarn guide may be chosen to provide steps ofvarying length and height in the same approximate helix.

The lapping movements of the third or laying-in guide bar in knittingthe fabrics of FIGS. 2a and 2b, respectively, will be evident from thepoint diagrams of FIGS. 3a and 3b, respectively. The movements of theother two guide bars which knit plain chains of warp stitches on thesame needles in an obvious manner have not been shown.

The laying-in guide bar makes a fall plate loop over the needles of thefront bed F while moving along the needle beds in one longitudinaldirection, but does not perform lapping movements relative to theneedles of the rear bed R which are longitudinally interposed betweenthe active needles for the front bed. This movement of the third guidebar is indicated by a solid line in each of FIGS. 3a and 3b. The returnmovement of the third guide bar is controlled in such a manner that fallplate loops are made on the active knitting needles of the rear bed R,while no lapping movements are performed relative to the front bedneedles. This is shown in broken lines in FIGS. 3a and 3b. FIGS. 3a and3b respectively correspond to the fabrics of FIGS. 2a and 2b.

A fabric of the invention consisting of six chains of warp stitches anda single laid-in yarn arranged in a helix of steeppitch, that is, awalewise offset by one course in each chain, may be produced byrepeating shogging motions of three guide bars in the following pattern,the middle bar being threaded with the sole laying-in yarn:

Front guide bar: 2-0/0-0/0-2/0-0/ Middle barO-O/2-2/2Z/4-4/4-4/6-6/4-4/4-4/2-2/ 2-2/ Rear guide bar: OO/OLZ/O-O/Z-O/ The distance between successive turns of the helix asmeasured along each chain is tive stitches in the tubular net soproduced.

The most important advantages of this invention are achieved if thefabric essentially consists of the several chains of warp stitches and asingle laid-in yarn. If a net of greater strength or of smaller meshsize is desired, more than one laid-in yarn may be used to form a doublehelix in an obvious manner. Many tubular nets of the invention may beproduced side by side on the same pair of needle beds by means of threesuitably threaded guide bars as will be obvious to those skilled in theart, the above decription being limited to the manner of producing oneofthe several nets which simultaneously come from the knitting machinein continuous strands and may be cut to a desired length or otherwiseyprocessed in a manner not directly relevant to this invention.

What is claimed is:

1. A method of operating a warp knitting machine having three guide barsand two needle beds, yarn guides and knitting needles on said guide barsand said needle beds respectively, and actuating means for operatingsaid guide bars and said knitting needles, only one of said guide barsbeing threaded with a laying-in yarn, the actuating means beig operativefor knitting two layers of warp chains on said needle beds respectively,and for connecting said warp chains into a tubular fabric by portions ofsaid layingyarn extending coursewise between said chains, theimprovement which comprises:

(a) offsetting sequential portions of said laying-in yarn in a commonwalewise direction,

( l) each of said portions being laid coursewise between a plurality ofrespective stitches of said chains aligned in a coursewise direction,and bound with said aligned stitches.

2. A method as set forth in claim 1, wherein said one guide bar makeslapping movements for looping said laying-in yarn about the needles ofone of said beds, while the laying-in yarn is prevented from makingloops about the needles of the other bed, while said one guide bar movescoursewise along said needle beds in one direction, said one guide barmaking lapping movements for looping said laying-in yarn about theneedles of the other needle bed while said laying-in yarn is preventedfrom making loops about the needles of said one needle bed while saidone guide bar moves in a coursewise direction opposite to said onedirection.

References Cited UNITED STATES PATENTS Re. 26,496 12./1968 Krauss 66-193459,866 9/1891 Clewley 66-170 3,178,910 4/1965 Hammerle 66-190X3,251,201 5/1966 Newman 66--192 3,513,668 5/1970 Mintz 66-193 RONALDFELDBAUM, Primary Examiner

